308 resultados para EXCITED-STATE INTERACTIONS


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Sao Paulo state, Brazil, is one of the main areas of sugar cane agriculture in the world. Herbicides, in particular, ametryn, are extensively used in this extensive area, which implies that this herbicide is present in the environment and can contaminate the surface water by running off. Thereby, residues of ametryn were analyzed in samples of river water an river sediment and in freshwater bivalves obtained from the rivers Sapucai, Pardo and Mogi-Guacu in Sao Paulo State, Brazil. Samples were taken in the winter of 2003 and 2004 in two locations in each river. The specimens of freshwater bivalves collected and analyzed were Corbicula fluminea, an exotic species, and Diplodon fontaineanus, a native species. Additionally, the evaluation of the ability of bioconcentration and depuration of ametryn by the freshwater bivalve Corbicula fluminea was also performed. Ametryn concentrations in the samples were measured by liquid chromatography coupled to mass spectrometry. Residues of ametryn in water (50 ng/L) and in freshwater bivalves (2-7 ng/g) were found in the Mogi-Guacu River in 2004, and residues in river sediments were found in all rivers in 2003 and 2004 (0.5-2 ng/g). The observation of the aquatic environment through the analysis of these matrixes, water, sediment, and bivalves, revealed the importance of the river sediment in the accumulation of the herbicide ametryn, which can contaminate the biota.

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This work reports oil a novel nitrosyl-ruthenium complex hearing the azanaphthalene ligand quinazoline (qui) ill its coordination sphere. The product crystallizes with ail additional quinazoline molecule, yielding the compound cis-[Ru(bpy)(2)(qui)NO](PF(6))(3).(qui). This feature leads to all absorption band at lambda(max) = 430 nm in CH(3)CN and lambda(max) = 420 nm in phosphate buffer, which promotes the photorelease of nitric oxide under visible light irradiation (lambda > 400 nm), in 1 ethanol: 1 water (v/v) mixture or under physiological pH. Both the intensity and energy of this transition are dependent on solvent and solution pH, suggesting that the transition has a charge transfer nature, and that the association of the second quinazoline molecule with the complex is driven by weak interactions, possibly of the pi-stacking type. (C) 2009 Elsevier Ltd. All rights reserved.

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Recently, some research groups have been developing studies aiming to apply spouted beds of inert particles for production of dried herbal extracts. However, mainly due to their complex composition, several problems arise during the spouted bed drying of herbal extracts such as bed instability, product accumulation, particle agglomeration, and bed collapse. The addition of drying carriers, like colloidal silicon dioxide, to the extractive solution can minimize these unwanted effects. The aim of this work was to study the influence of the addition of colloidal silicon dioxide on enhancement of the performance of the drying of hydroalcoholic extract of Bauhinia forficata Link on a spouted bed of inert particles. The physical properties of the herbal extract and of its mixture with colloidal silicon dioxide at several concentrations (20% to 80% related to solids content) were quantified by determination of the surface tension, rheological properties, density, pH, and contact angles with the inert surfaces. Drying performance was evaluated through determination of the elutriation ratio, product recovery ratio, and product accumulation. The product was characterized through determination of the thermal degradation of bioactive compounds and product moisture content. The results indicated that the rheological properties of the extracts and their preparations, the contact angle with inert material, and the work of adhesion play important roles in the spouted bed drying of herbal extracts. Higher concentration of the drying carrier significantly improved the spouted bed drying performance.

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Budlein A has been reported to exert some analgesic and anti-inflammatory properties. In this study, we have evaluated its effect on LPS-induced leukocyte recruitment in vivo and the mechanisms involved in its anti-inflammatory activity. In vivo, intravital videomicroscopy was used to determine the effects of budlein A on LPS-induced leukocyte-endothelial cell interactions in the murine cremasteric microcirculation. In vitro, the effects of budlein A on LPS-induced cytokine, chemokine and nitrites release, T-cell proliferative response as well as cell adhesion molecule expression (CAM) were evaluated. In vivo, intraperitoneal administration of budlein A (2.6 mM/kg) caused a significant reduction of LPS-induced leukocyte rolling flux, adhesion and emigration by 84, 92 and 96% respectively. In vitro, T-cell proliferative response was also affected by budlein A. When murine J774 macrophages were incubated with the sesquiterpene lactone, LPS-induced IL-1 beta, tumor necrosis factor-alpha (TNF-alpha) and keratinocyte-derived chemokine (KC) release were concentration-dependently inhibited. In human umbilical vein endothelial cells (HUVECs), budlein A also reduced the production of TNF-alpha, monocyte chemoattractant protein-1 (MCP-1), IL-8, nitrites and CAM expression elicited by LPS. Budlein A is a potent inhibitor of LPS-induced leukocyte accumulation in vivo. This effect appears to be mediated through inhibition of cytokine and chemokine release and down-regulation of CAM expression. Thus, it has potential therapeutic interest for the control of leukocyte recruitment that occurs in different inflammatory disorders. (C) 2009 Elsevier GrnbH. All rights reserved.

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The feasibility of detecting instability in wet spouted beds via pressure fluctuation (PF) time-series analyses was investigated. Experiments were carried out in a cylindrical Plexiglas column of diameter 150 mm with a conical base of internal angle 60 degrees, an inlet orifice diameter of 25 mm and glass beads of diameter 2.4 mm. Transducers at several axial positions measured PF time series with incremental addition of aqueous sucrose solutions of different concentrations. Liquid addition affected the spouted bed dynamics, causing irregular spouting, increased voidage in the annulus, increased fountain height, irregular annulus height, channelling, agglomeration, and adhesion of particles to the column walls. Autocorrelations indicated the appearance of periodicities in the PF signals with increasing sucrose addition. Dominant peaks in power-spectral density developed at low frequencies with changing system dynamics. The results indicate that PF signals furnish relevant information on system dynamics, useful for monitoring and control of spouted bed operations such as particle coating and drying of paste-like materials.

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Inclusion complexes of Lippia sidoides essential oil and beta-cyclodextrin were obtained by slurry method and its solid powdered form was prepared using spray drying. The influence of the spray drying, as well as the different essential oil:beta-cyclodextrin ratio on the characteristics of the final product was investigated. With regard to the total oil retention 1:10 mass/mass ratio as optimal was found between the essential oil and beta-cyclodextrin. Thermoanalytical techniques (TG, EGD, TG-MS) were used to support the formation of inclusion complex and to examine their physicochemical properties after accelerated storage conditions. It may be assumed that the thermal properties of the complexes were influenced not only by the different essential oil/beta-cyclodextrin ratio but also by the storage conditions. In the aspect of their thermal stabilities, complex prepared with 1:10 m/m ratio (essential oil: beta-cyclodextrin) was the most stable one.

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Uranium is a natural radioactive metallic element; its effect on the organism is cumulative, and chronic exposure to this element can induce carcinogenesis. Three cities of the Amazon region-Monte Alegre, Prainha, and Alenquer-in North Brazil, are located in one of the largest uranium mineralization areas of the world. Radon is a radioactive gas, part of uranium decay series and readily diffuses through rock. In Monte Alegre, most of the houses are built of rocks removed from the Earth`s crust in the forest, where the uranium reserves lie. The objective of the present work is to determine the presence or absence of genotoxicity and risk of carcinogenesis induced by natural exposure to uranium and radon in the populations of these three cities. The frequency of micronuclei (MN) and chromosomal aberrations (CA) showed no statistically significant differences between the control population and the three study populations (P > 0.05). MN was also analyzed using the fluorescence in situ hybridization (FISH) technique, with a centromere-specific probe. No clastogenic and/or aneugenic effects were found in the populations. Using FISH analysis, other carcinogenesis biomarkers were analyzed, but neither the presence of the IGH/BCL2 translocation nor an amplification of the MYC gene and 22q21 region was detected. Clastogenicity and DNA damage were also not found in the populations analyzed using the alkaline comet assay. The mitotic index showed no cytotoxicity in the analyzed individuals` lymphocytes. Once we do not have data concerning radiation doses from other sources, such as cosmic rays, potassium, thorium, or anthropogenic sources, it is hard to determine if uranium emissions in this geographic region where our study population lives are too low to cause significant DNA damage. Regardless, genetic analyses suggest that the radiation in our study area is not high enough to induce DNA alterations or to interfere with mitotic apparatus formation. It is also possible that damages caused by radiation doses undergo cellular repair.

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Aiming at international competitiveness of the Brazilian dairy sector, new governmental policies were released to improve quality and safety of bovine milk. In this context, it is important to quantify essential and toxic chemical elements. Here, the composition of milk samples taken at 32 dairy farms in Minas Gerais State was assessed by instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS), besides the evaluation of usual quality parameters. Significant differences were found for Ba, K, Na and fat content amongst dairy farms with diverse quality levels established on basis of somatic cell and total bacterial count.